Composition and classification of pearlescent pigments

Pearlescent pigments are composed of several metal oxides coated with thin layers of mica. By changing the thin metal oxide layer, different pearlescent effects can be produced. Compared with other pigments, pearlescent pigments have an unparalleled effect of their unique soft pearl luster. The special surface structure, high refractive index and good transparency allow it to create the same effect as pearl luster in transparent media. The excellent chemical resistance and high temperature resistance of pearlescent pigments provide the possibility of its wide application in coatings, inks, plastics and various fields, and they provide a whole new color system and color quality for these products. Pearlescent pigments have low heavy metal content and meet relevant safety technical standards, so they can be used in food packaging and children's toys. At room temperature, neither acid nor alkali can erode pearlescent pigments. Pearlescent pigments are non-flammable, non-spontaneous, non-conductive, and can withstand high temperatures of 600-800 °C. Pearlescent pigments can also be used in reactive coatings in radiation curing systems (electron beam curing, light curing). The special surface chemical structure of pearlescent pigment makes it have excellent hydrophilicity, so it can be applied to water-based paint, but it has poor lipophilicity, so when it is used in organic system, there will be a problem of poor dispersibility, and surface treatment of pearlescent pigment is required. , so that it can also be well used in organic systems.

Pearlescent pigments are mainly divided into the following categories:
1. Pearlescent powder
Pearlescent powder is divided into ordinary powdered pearlescent materials and pearlescent balls dispersed with soft resin. The colors mainly include silver, bright gold, metallic color, rainbow interference color and chameleon series. Among them, pearlescent powder is different according to the direction of use and the effect of use. The distinction of particle size, the smaller the particle size, the stronger the hiding power of the pearlescent powder; the larger the particle size, the stronger the gloss of the pearlescent powder; the particle size in the printing industry has stricter requirements, and the small particle size can be used for offset printing. Larger particle sizes can be used for flexo and gravure printing with better results.
2. Pearlescent paste
Pearlescent paste is a high-viscosity pearlescent material, which is more suitable for mixing with offset printing ink. It has excellent hiding power and good gloss, and is suitable for offset printing.